I. Field of the Invention
The present invention relates generally to a brush and particularly to a brush bristle cluster and its association with a brush handle. The present invention has particular, although not exclusive, utility in the field of paint brushes.
II. Description of Related Art
FIGS. 1A to 1C illustrate a known brush construction. The brush 1 shown in FIG. 1C comprises a main body portion 2 and a bristle cluster 7.
Referring first to FIG. 1A the body portion 2 has a handle portion 3 and an enlarged head portion 4 terminating with a flat abutment surface 4a. A metal ferrule 5 surrounds the head portion 4 and extends beyond the surface 4a to form a rebate 6.
Referring now to FIG. 1B the bristle cluster 7 comprises a plurality of bristles and has a tip end 8 terminating at a tip end terminus point 8a defining the maximum extent of the cluster tip, and a root end 9 terminating at a root end terminus point 9a defining the maximum extent of the cluster root.
In this example the cluster 7 comprises bristles 10 of three different lengths: the longest bristles 10a have a length L1; the middle length bristles 10b have a length L2; and the shortest bristles 10c have a length L3. The length L1 is 10 mm greater than the length L2 and the length L2 is 10 mm greater than the length L3. In practice, particularly where natural bristles are used, the number of different lengths of bristles may be far greater than three, but for the purposes of simplicity only three are referred to here.
Referring now also to FIG. 1C the root end 9 of the bristle cluster 7 is received in the rebate 6 and either resin (not shown) is filled into the rebate 6 or the end of the cluster 7 is first dipped into resin and then inserted into the rebate to adhere the bristle ends both together and to the ferrule 5 and the head portion 4. The root end 9 of the bristle cluster 7 is set into the resin bed by a set depth defined by the rebate 6, which in this case is 8 mm.
A setting region within which bristle ends at the root end 9 are embedded in resin therefore extends for 8 mm from the abutment surface 4a to the open end of the rebate 6. Bristles commencing at the point 9a are therefore embedded in resin to a maximum extent.
The longest bristles 10a commence at the point 9a and terminate at the point 8a and therefore are inserted in the setting region 11 to the maximum set depth of 8 mm. Accordingly, only bristles having a length greater than L1 minus 5 mm are guaranteed to be embedded within the resin to at least some extent. This is because shorter bristles can terminate at any point up to the tip end terminus point 8a of the cluster and only extend from there to commence at a point at the root end 9 as determined by their length. For example, a bristle 10b terminating at the tip end terminus point 8a would only commence 2 mm away from the start of the region 11 and would not be embedded. Bristles 10b and 10c have a length less than L1 minus 8 mm are therefore not guaranteed to be embedded within the resin; whether they are or not will depend on their longitudinal position within the cluster (i.e. where they commence and terminate relative to the points 8a, 9a).
As shown in FIG. 1C, some of the bristles 10b, 10c do not commence within the setting region 11 and are therefore not embedded in resin. These bristles may fall out of the cluster in use of the brush.
In order to attempt to prevent bristle loss of the type described in relation to FIGS. 1A to 1C the brush 101 shown in FIG. 2 was developed, The brush 101 is similar to the brush 1 shown in FIG. 1 with the exception of the bristle cluster 107. The cluster 107 comprises bristles 120 which are all approximately the same length and all commence and terminate at or close to the tip end 108a and root end points 109a respectively. In this case the set depth is 10 mm and accordingly when the root end 109 is inserted into the rebate 106 so that the point 109a abuts against the surface 104a all bristles 120 in the cluster 107 are maximally inserted into the setting region 111 and bristle loss during use is minimised.
However, because all bristles terminate at the point 108a it has been found that brushes using the principles of FIG. 2 can feel “tip heavy” in use when compared to brushes of the type shown in FIG. 1C, for example, in which due to the variation in bristle lengths the tip end does not include terminal segments of all bristles.